This invention relates devices for providing control without the need of one's hands. More particularly it relates to intraoral control devices.
When high level spinal cord injured individuals lose the ability to control their upper extremities, they are left with no way to perform activities of daily living. Functional electrical stimulation of the muscles of the upper extremities and hands is currently being investigated as a means of allowing the high level quadriplegic to regain the use of their upper extremities and hands. However it is difficult to transmit the desired information for such stimulation from the brain, bypassing the spinal injury, directly to devices which provide the electrical stimulation. Furthermore control of movement in the upper extremities and hands when performing activities of daily living is a much more complex task than control of movement of lower extremities during ambulation. The simultaneous contraction of muscles of the hand, the wrist, and elbow while performing a complex movement makes their control very difficult. There is a constant need for complex proprioceptive kinesthetic and other sensory feedback to modify simultaneous muscle contractions.
Nonimpaired functions of a high quadriplegic are best utilized in order to control electrical stimulation of the arms and hands and other devices. Two functions which are not impaired as a result of a high level spinal injury are jaw movement and tongue movement. Even if electrical stimulation of muscles in the upper extremities and hands proves not to be completely successful, the high level quadriplegic still has the need to control other devices in order to function more independently.
Apparatus associated with the use of tongue or jaw movement are referred to as intraoral controllers. An attempt was made to develop an intraoral controller between 1966 and 1970 as part of a large research project to develop an external orthotic device to allow high quadriplegics to move their upper extremities. The project was conducted by a medical engineering research group at Rancho Los Amigos Hospital in Los Angeles, Calif. with Vernon L. Nichols MD being the principal investigator and the University of Michigan Dental School at Ann Arbor, Mich. with Major M. Ashe, DDS as the principal dental consultant. Six sets of magnetic flux sensitive resistors were used to control the velocity in a corresponding electrically powered arm brace which was also under development. The first attempt was to place the sensors on a partial dental plate in the mandible with movement of a magnet by the tongue. Implantation of the magnet into the tongue was tried on several dogs, however subsequent fibrosis around the magnet implant and a breakdown of its stainless steel coating became a problem. A second strategy was then tried by placing the 16 magnetic flux sensitive resistors on a maxillary partial dental plate with magnets placed on a similar mandibular partial denture. In the same project an attempt was also made to develop pressure sensitive sensors which could be activated by the tongue on a maxillary partial denture. None of those strategies proved successful in developing a useful intraoral controller.
In 1978, a device called a tongue activated computer controller (TACC) was developed by Daniel Fortune for a high level quadriplegic. The controller consisted of a set of ten 1/4" diameter switches placed 1/4" apart on a surface under the hard and soft palates. It was demonstrated that, with practice, the tongue could operate the switches with approximately 70% accuracy.
Another attempt at developing an intraoral controller was made at Stanford University in 1982 and 1983. The Stanford controller consisted of a palatial splint with two mircoswitches mounted on a bite block and a two axis piezoresistive transducer placed between the upper and lower teeth in a space below the hard palate. The microswitches were operated by jaw movement. The two axis transducer was operated by the tongue, however the transducer was quite large making it bulky and aesthetically unsatisfactory. Another attempt was also made at Stanford University using a series of microswitches on a palatial splint, however those switches experienced corrosion problems.
The patent literature reveals various attempts at intraoral controllers. U.S. Pat. Nos. 4,605,927 and 4,783,654 issued to Philip Katz et al show an intraoral control unit and system which utilizes on-off switches and which generate FM signals from inside the mouth to an external FM receiver which in turn operates a controller for controlling various appliances such as a television, lights and bed positions controls. Physical contact by the tongue is required to operate the Katz switches
U.S. Pat. No. 4,629,424 issued to Lauks et al shows an intraoral ambient sensing device which utilizes a substrate having an FM transmitter attached thereto.
U.S. Pat. No. 4,728,812 issued to Sherif et al shows a oral machine controller operated by the teeth.
An article appearing in the Proceedings of the 33rd Annual Conference on Engineering in Medicine and Biology, 1980, Volume 22, by Swartz and Katz, discussed biofeedback devices for tongue placement evaluation therapy. In an article in the Proceedings of the 29th Annual Conference on Engineering in Medicine and Biology of 1976, Volume 18, by David J. Powner, a call system for quadriplegic patients is discussed.